extra 19 Flashcards
(24 cards)
capillaries
have intimate contact with tissue cells and serve cellular needs, become veins, huge surface area, connect arteries and veins, smallest and most abundant, provide direct access to cells
lumen
central blood containing space
increases NE released by a vasomotor neuron causes
media smooth muscle
vessel diameter
resistance
blood flow
increase
decrease
increase
decrease
as total vessel length increases, resistance
as total vessel length decreases, blood flow will
increase (direct relationship)
increase
venules
veins
form when capillary beds unite
formed when venules join, bp lower than in arteries
blood flow
blood pressure
resistance
-volume of blood flowing thru vessel, organ, circ
-force per unit area exerted on wall of blood vessels by blood
-opposition to blood flow, 3 sources of resistance: blood vessel length, blood vessel diameter, blood viscosity (blood vessel diameter is the most important)
the longer the vessel
the greater the resistance
length and resistance are equal
growth and pregnancy increase length
vessel diameter
greatest influence on resistance, vasoconstriction increases resistance
if bp increases, blood flow
if PR increases, blood flow
increases
decrease
systemic bp
arterial bp
pumping action of heart generates blood flow, highest in aorta
reflects 2 factors of arteries: elasticity, volume of blood forced into them
systolic pressure
diastolic pressure
pressure exerted in aorta during v.contraction
lowest level of aortic pressure
pulse
created by throbbing arteries, measured in brachial artery, varies directly with heart
MAP
pressure that propels blood to tissues
an increase in sympathetic activity cause
increase in NE release on medium and large veins
increases vasomotor activity -> ___ ->__–>__–>___
increases sympathetic
vasoconstriction
increased PR
increased BP
NE=constriction->decrease in diameter->increase PR
neural controls
maintain MAP by altering blood vessel diameter, alter blood distribution to organs in response to demand
baroreceptor reflexes
chemoreceptor reflexes
increase input to vasomotor center
-detect increase in C02 or drop in pH or 02
auto regulation
adjustment of blood flow to each tissue, 2 types: metabolic (vasodilation of arteries) and myogenic
tissue perfusion involved in
delivery of 02 and nutrients, gas exchange, absorption, urine formation
capillary exchange
between plasma and tissue fluid, nutrients, wastes, and signaling molecules, 4 forces: capillary osmotic p (caused by albumin), capillary hydrostatic p (same as capillary bp), interstitial osmotic p (caused by solutes), interstitial hydrostatic p (caused by cells pushing on vessels)
hypovelmic
large blood loss
long term control of bp; direct and indirect
direct: alters bv
indirect: renin-a-a
ag II
acts as vasoconstrictor, promotes release of aldosterone and antidiuretic hormone
hypotension
hypertension
low bp
high bp
